Electrical conductor terminal clamp



June 22, 1965 c. P. COLDREN ELECTRICAL CONDUCTOR TERMINAL CLAMP Filed June 5, 1965 INVENTOR. CHESTER D. COLDIZEN United States Patent ELECTRECAL 'CQNDUCTGR TERMTNAL CLAMP Chester P. Coldren, Canton, Ohio, assignor to Eaton Manufacturing Company, a corporation of Ohio Filed June 5, 1963, Ser. No. 285,673 9 Claims. (Cl. 339-2 36) This invention relates, as indicated, to a terminal clamp, and more particularly to an electrical conductor terminal clamp which is particularly adapted for use in clamping a single electrical conductor, or a plurality of electrical conductors to a terminal bar or lug. Where two or more electrical conductors are sought to be secured to such a terminal, the devices of the present invention are especially useful where such conductors have different sizes or are differently formed such as one conductor being a single Wire and the other a plurality of strands of wire.

In the past, difficulty has been experienced with terminal clamps in respect to their ability to hold electrical conductors, and especially under conditions where only one electrical conductor is being held by the clamp, or where a pair of electrical conductors are being held by the same clamp and the conductors have different diameters or are composed differently, as for example by one of the conductors being a single electrical wire conductor, and the other being of the cable type formed from a plurality of wire strands. Such conductor combinations result in the terminal clamp exerting uneven pressures on the conductor which are disposed on opposite sides of the retaining bolt with the consequence that the connections are not sufficient to pass the rigid requirements of underwriting organizations. To meet these requirements, the fastening component of the clamp must permit the adjoining members to rock freely or otherwise center themselves when being tightened.

The present invention provides improved structure for the components of an electrical conductor terminal clamp of the self-centering type, and which is characterized by an assembly including a bolt, a washer and a saddle, and in which the relationship between the bearing surface of the bolt and the bearing surface of the Washer is such that these elements are brought into tight engagement with each other along a curved path, and preferably along a circular linear path. In other words, the bearing surface of the washer element is not beveled or shaped in any way for mating engagement with the bearing surface of the retaining bolt. Instead, the contact between these parts is along a sharp edge surrounding the aperture through the washer.

The present invention may be better understood by having reference to the annexed drawings in which:

FIG. 1 is a partial cross-sectional view of an electrical conductor terminal clamp of the present invention showing the bolt, the washer and the saddle in assembled condition, the parts being loosely, but inseparably retained as shown in FIG. 1.

FIG. 2 is an elevation of the underside of the saddle of the electrical conductor terminal clamp showing conductor engaging ribs disposed on either side of the slot through the saddle.

FIG. 3 is a plan view of a washer having a sharp hearing edge for coaction with the bearing surface of the bolt as shown in FIG. 1.

FIG. 4 shows a saddle blank stamping from which a preferred form of the saddle is formed by bending flange portions out of the plane of the blank in the manner shown in FIG. 1.

FIG. 5 is a cross-sectional view of the saddle blank taken in the plane indicated by the line 5-5 in FIG. 4, and showing the displacement of the rib embossment out of the plane of the blank which improves the rigidity of the saddle.

3,191,140 Patented June 22, 1965 Fee FIG. 6 is a fragmentary perspective view of a terminal connector block showing the clamps of the present invention operatively disposed for clamping a pair of wires, and a single wire, one of the pair of clamped wires being of the multistrand or cable type.

Briefly stated, the present invention is in the provision of an electrical conductor terminal clamp comprising in combination a saddle having a centrally disposed elongated slot. To fasten the clamp to the terminal bar or lug, there is provided a bolt extending through the slot and having a head portion, a convex bearing surface adjacent the head portion, and a shank having a neck portion adapted to move freely in the slot. Between the bearing surface of the bolt and the saddle, there is provided a substantially rigid washer having an internal diameter larger than the neck portion of the shank in order that there may be free movement of the washer relative to the shank. The internal diameter of the washer is smaller than the maxi mum diameter of the bearing surface in order that the washer is securely held between the head of the bolt and the saddle. The washers of the present invention are substantially rigid and are characterized in that they have, contrary to the structures of the prior art, a sharp bearing edge shaped for curvilinear contact with the convex bearing surface of the bolt. The opposite surface of the wash er adjacent the aperture is shaped for coaction with the saddle over a substantial area of contact as distinguished from the minimal engagement of the bearing edge against the convex bearing surface. In more specific embodiments of the present invention, means are also provided for maintaining the bolt, the washer and the saddle in loose, but inseparable assembly. 7

Referring now more particularly to FIG. 1, there is here shown on an enlarged scale an electrical conductor terminal clamp assembly of the present invention in which there is provided a bolt 10, a saddle 11 and a washer 12.

Bolt 10 includes a head portion 13 having any suitable means for driving the bolt, such as a screw driver receiving slot 14%, a bearing surface 15 and a shank 16. Shank 16 is provided with an unthreaded neck portion 17 and a threaded portion 18. For purposes which will be hereinafter more fully explained, shank 10 is also provided with retaining means to secure the bolt 10 in assembled relation with the saddle 11 and the washer 12, which in the preferred embodiment is in the form of a 360 thread 19.

The bearing surface 15 of the bolt 10 is a convex surface, and most desirably a spherical segment of two bases 20 and 21. Base 20 is adjacent the head portion 13 of bolt 1!], and base 21 adjoins the shank portion 16.

Saddle 11 is conveniently formed from a stamped embossed blank having the configuration shown in FIG. 4 and including a bridging portion 22, an elongated slot 23 and a pair of flange portions 24 and 25 adapted to overlap a terminal lug or bar, such as the terminal lug 26 in FIG. 6.

In the preferred embodiment shown in the drawings, the underside of the bridging portion 22 of the saddle 11 is desirably provided with embossed conductor engaging and retaining means, preferably in the form of V-shaped elongated conductor engaging ribs 27 disposed on opposite sides of slot 23. While two such ribs 27 have been shown in each side of slot 23, one or more of such conductor engaging and retaining ribs 27 may be embossed thereon. Ribs 27 are positioned on the underside of saddle 11 so that they will lie across the conductor or conductors. The projecting edges of the V will be forced into interlocking engagement with the conductors at preferably two spaced points and will deform the metal of the conductor at the intersection of the rib therewith. In this way a strong pull resistant clamping is secured.

With respect to conductor retaining ribs 27, it has been found that better pull test results are secured when the faces of the embossed conductor engaging and reto form the saddle 11.

I v 3 I taining ribs forming the V-shape are disposed relative to each other at an angle which is in the range of from about 90 to about 135.

The embossmentresulting in the raised ribs 27 on the underside of saddle 11 is also conveniently provided with a bridge 35 joining the two spaced apart rib embossments 36' and 37 Bridge 35 helps to stregnthen the saddle 11.

I Saddle 11 is, as indicated above, provided with an elongated slot 23 which has a major axis sutlicient to allow a rocking or self-centering action by the saddle 11 relative to the neck portion 17 of bolt 10. The minoraxis of the elongated slot 23 is less than the major diameter of the threaded portion 18 of theshankld as bestshown in FIG. 2.

In order to maintain the principal components in loose, but inseparable assembly, there is provided a 360 thread .19 between the neck portion 17 and the threaded portion 18. The purpose of 360 thread 19 is to eliminate the normal thread lead which can coact with the elongated slot 23- and ultimately enable'zthe bolt to become separated from the saddle 11.v Instead of the more convenient 360 thread 19, shank portion 16 may be provided with any other suitable shoulder means or retaining means for keeping the bolt 10 in assembled relation with the washer 12 and the saddle 11 I I Washer 1-2 in the preferred embodiment is conveniently a plain washer, the internal diameter of which is larger than the diameter of neck portion 17, and less than the diameter of the larger diameter base 20 of the spherical segment bearing'surface 1'5. Plain washer 12 is provided with a sharp bearing edge 30 as distinct from a beveled or contoured bearing surface on the washers or collars. Thus, when the bolt 10 is tightened down into a terminal bar or lug, such as lug 26 (FIG. 6), washer12 contacts bearing surface along a curvilinear line, and specifical- These devices are capable of securing wires of different sizes toterminals so as towithstand the requirements of established pull tests. Also, these devices have the advantage that when shipped in cartons, they do not become disassembled, as is oftentimes the case where threads 18 are rolled in the normal fashion, that is with the usual lead. I These devices also have the advantage that because of the shat bearing edge on washer 12 roviding I required with structures where the bearing surface of the 1y along a circular path of minimum width, i.e. substantially line contact; Through coaction with the preferred spherical segment 15, the contact pressure at all points along the contact bearing edge 30 and the spherical segment 15 i-s unif-orm. At the same time, because of the large internal diameter of the washer 12, the washer-sack dle assembly is permitted to rock or center itself with respect to the electrical conductors without loss of clamping, pressure. Whilethere has been shown a continuous circular bearing edge 30, it will be under-stood that thebearing edge may be made discontinuousas by filing the edge away at spaced intervals. I f

FIG. 6 shows a terminal block having three terminal lugs or bars 26 extending therefrom. The right hand lug 26 shows the provision of atapped hole 31 which is threaded to receive the bolt 10 shown in FIG. '1. The middle lug 26 is shown with single wire electrical conductor 32 clamped thereto, and illustrating the self-centering and rocking characteristics of the improved clamps of this invention. Thus, the saddle 11 is raised on its right hand side to accommodate the conductor 32, and depressed on its left hand side where there is no, conductor provided. I

' The left hand lug 26 is. shown having conductors 33 and 34 clamped the'retoby a clamp, such as that shown in FIG. 1. Conductor 33 is of the multi'strand electrical con.-

' 'ductortyp'e, and conductor 34'is a single wire conductor procedures. WasherlZ and a bolt 13, in blank form, that V is with no threads formed thereon, are disposed in assembled relation with the blank as shownin FIG. 4. This assembly is then fed through a thread rolling machine to apply the threads 18 to a portion of the shank 16, and a simultaneously apply the 360 thread 19.: Following the threading operation, the assembly is then passed into a. bending machine Wh6l6 the flanges 24 and 25 are rolled washer 12, for example, is beveled to correspond with the bearing surface of the bolt 10. I

I It has been found that in order to obtain good seating and clamping, with the least amount of driving torque,

ing of the washer against the bearing surface of the bolt.

Other modes of applying the principle of this invention may be employed instead of those specifically set forth above, changes being made 'asregards the details herein disclosed; provided the elements set forth in any of the following claims, or the equivalent of such be employed. It is, therefore, particularly pointed out and distinctly claimed as the invention.

1. An electrical conductor terminal clamp comprising in combination:

(a) a saddle having a centrally disposed elongated slot andhaving a terminal-bridging portion and depending flange portions; a (b) a bolt for fastening said clamp to saidterminal, the free end of said bolt extending through said slot and having,

(1) a head, I I (2) a convex bearing surface on the underside of said head, and V 3) a shankhaving a neck portion thereof depending from said convex bearing surface and so shaped as to movefreely'in said elongated slot ofsaid saddle;

' .(c) a substantially rigid washer disposed between said convex bearing surface and said saddle, and having an 'aperture'oversized relative to said shank forcanting movement relative .to said shank and sliding movement relative to the saddle, portions of the surfaces of said washer adjacent the aperture forming contact portions with the convex bearing surface and the saddle, respectively, and being shaped for substantial line contact with said convex bearing surface and substantial area contact with said saddle in various angular dispositions relative to the axis of said bolt. I 2. An electrical conductor in combination: I w p (a), a saddle having a centrally disposedel-ongated slot and having a terminal-bridging portion and depending flange portions; l e (b) a boltfor fastening said clamp to said terminal, the V free end of said bolt extending through said slot and having V I l (l) ahead,

I (2). a convex bearing surface on the underside of saidhead, and I (3) a shank having a neck portion thereof dependterminal clamp comprising ing from said convex bearing surface and so shaped as to move freely in said elongated slot of said saddle;

(c) a substantially rigid washer disposed between said convex bearing surface and said saddle, and having an aperture oversized relative to said shank for cant ing movement relative to said shank and sliding movement relative to the saddle, portions of the surfaces of said washer adjacent the aperture forming contact portions with the convex bearing surface and the saddle, respectively, and being shaped for substantial line contact with said convex bearing surface and substantial area contact with said saddle in various angular dispositions relative to the axis of said bolt; and

(d) mean for maintaining said saddle, bolt and washer in loose captive assembly.

3. A terminal clamp in accordance with claim 2 in which the assembly maintaining means is a 360 shoulder surrounding said shank having a diameter greater than the width of the slot in the saddle.

4. A terminal clamp in accordance with claim 3 in which the 360 shoulder is a 360 thread.

5. A terminal clamp in accordance with claim 2 wherein the saddle is provided with conductor-gripping means integral therewith.

6. A terminal clamp in accordance with claim 5 Wherein the gripping means includes a pair of conductor-engaging ribs on the underside of said saddle disposed respectively on either side of said slot, and adapted to engage an electrical conductor transversely of the axis thereof.

7. A terminal clamp in accordance with claim 6 wherein the conductor-engaging surface of said ribs is provided with a straight V-thread in which the angle of the V is from 90 to 130.

8. An electrical conductor terminal clamp comprising in combination:

(a) a saddle having a terminal bridging portion, a

centrally disposed elongated slot in said bridging portion, a pair of terminal-overlapping flange portions depending from opposed marginal extremities of said bridging portion which marginal extremities are perpendicular to the major axis of said slot, and embossed conductor-engaging and retaining means on the underside of said bridging portion;

(b) a bolt for fastening said clamp to said terminal and having a head portion, a bearing surface on the underside of said head portion and having a geometric configuration of a spherical segment having two bases, the larger base being adjacent said head portion, and a shank having a neck portion adapted to move freely in said elongated slot, extending from the smaller of said bases; and

(c) a circular substantially rigid washer disposed between said bearing surface and the upper side of said saddle bridge portion, said washer having an internal diameter larger than said shank neck portion for free canting movement of said washer relative to said shank and sliding movement relative to said saddle,

said internal diameter being less than the diameter of said larger base of said bearing surface, portions of the surfaces of said washer adjacent the aperture forming contact portions with the spherical bearing surface and the saddle, respectively, being shaped for contacting said spherical bearing surface along a circular contact line and said saddle over a substantial area of contact in various angular dispositions relative to the axis of said bolt.

9. An electrical conductor terminal clamp comprising in combination:

(a) .a saddle having a terminal-bridging portion, a centrally disposed elongated slot in said bridging portion, a pair of terminal-overlapping flange portions depending from opposed marginal extremities of said bridging portion which marginal extremities are perpendicular to the major axis of said slot, and embossed conductor-engaging and retaining means on the underside of said bridging portion;

(b) a bolt for fastening said clamp to said terminal and having a head portion, a bearing surface on the underside of said head portion and having a spherical configuration, and a shank having an unthreaded neck portion extending from said bearing surface and a threaded continuation of said neck portion adapted to be threadedly engaged in said terminal, said threaded portion being separated from said unthreaded portion by a 360 thread having a major diameter greater than the Width of said elongated slot whereby said bolt is loosely and captively retained in said saddle, and

(c) a circular substantially rigid washer disposed between said bearing surface and the upper side of said saddle bridge portion, said washer having an internal diameter larger than said shank neck portion for free canting movement of said washer relative to said shank and sliding movement relative to said saddle, said internal diameter being less than the diameter of the larger base of said bearing surface, portions of the surfaces of said washer adjacent the aperture forming contact portions with the spherical bearing surface and the saddle, respectively, being shaped for contacting said spherical bearing surface along a circular contact line and said saddle over a substantial area of contact in various angular dispositions relative to the axis of said bolt.

References Cited by the Examiner UNITED STATES PATENTS 812,287 2/06 Nagel 339246 895,714 8/08 Babcock et a1 339266 2,304,711 12/42 Shenton 339--266 2,712,167 7/55 Blanchard 339246 X 3,050,706 8/62 Kitscha 339246 3,068,445 12/62; Crowther 339246 FOREIGN PATENTS 289,816 7/53 Switzerland.

JOSEPH D. SEERS, Primary Examiner. 

1. AN ELECTRICAL CONDUCTOR TERMINAL CLAMP COMPRISING IN COMBINATION: (A) A SADDLE HAVING A CENTRALLY DISPOSED ELONGATED SLOT AND HAVING A TERMINAL-BRIDGING PORTION AND DEPENDING FLANGE PORTIONS; (BE A BOLT FOR FASTENING SAID CLAMP TO SAID TERMINAL, THE FREE END OF SAID BOLT EXTENDING THROUGH SAID SLOT AND HAVING, (1) A HEAD, (2E A CONVEX BEARING SURFACE ON THE UNDERSIDE OF SAID HEAD, AND (3) A SHANK HAVING A NECK PORTION THEREOF DEPENDING FROM SAID CONVEX BEARING SURFACE AND SO SHAPED AS TO MOVE FREELY IN SAID ELONGATED SLOT OF SAID SADDLE; (C) A SUBSTANTIALLY RIGID WASHER DISPOSED BETWEEN SAID CONVEX BEARING SURFACE AND SAID SADDLE, AND HAVING AN APERTURE OVERSIZED RELATIVE TO SAID SHANK FOR CANTING MOVEMENT RELATIVE TO SAID SHANK AND SLIDING MOVEMENT RELATIVE TO THE SADDLE, PORTIONS OF THE SURFACES OF SAID WASHER ADJACENT THE APERTURE FORMING CONTACT PORTIONS WITH THE CONVEX BEARING SURFACE AND THE SADDLE, RESPECTIVELY, AND BEING SHAPED FOR SUBSTANTIAL LINE CONTACT WITH SAID CONVEX BEARING SURFACE AND SUBSTANTIAL AREA CONTACT WITH SAID SADDLE IN VARIOUS ANGULAR DISPOSITIONS RELATIVE TO THE AXIS OF SAID BOLT. 